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Title: The emergent 1.1-1.7 μm spectrum of the exoplanet COROT-2B as measured using the Hubble space telescope

We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting, very hot Jupiter CoRoT-2b in the 1.1-1.7 μm spectral region. We find an eclipse depth averaged over this band equal to 395{sub −45}{sup +69} parts per million, equivalent to a blackbody temperature of 1788 ± 18 K. We study and characterize several WFC3 instrumental effects, especially the 'hook' phenomenon described by Deming et al. We use data from several transiting exoplanet systems to find a quantitative relation between the amplitude of the hook and the exposure level of a given pixel. Although the uncertainties in this relation are too large to allow us to develop an empirical correction for our data, our study provides a useful guide for optimizing exposure levels in future WFC3 observations. We derive the planet's spectrum using a differential method. The planet-to-star contrast increases to longer wavelength within the WFC3 bandpass, but without water absorption or emission to a 3σ limit of 85 ppm. The slope of the WFC3 spectrum is significantly less than the slope of the best-fit blackbody. We compare all existing eclipse data for this planet to a blackbody spectrum, and to spectra from both solar abundancemore » and carbon-rich (C/O = 1) models. A blackbody spectrum is an acceptable fit to the full data set. Extra continuous opacity due to clouds or haze, and flattened temperature profiles, are strong candidates to produce quasi-blackbody spectra, and to account for the amplitude of the optical eclipses. Our results show ambiguous evidence for a temperature inversion in this planet.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
  2. Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511 (United States)
  3. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544-1001 (United States)
  4. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
  5. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  6. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22351573
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 783; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABUNDANCE; AMPLITUDES; COMPARATIVE EVALUATIONS; CORRECTIONS; ECLIPSE; EMISSION; JUPITER PLANET; OPACITY; SATELLITE ATMOSPHERES; SATELLITES; SPACE; SPECTRA; STARS; TELESCOPES; TEMPERATURE INVERSIONS; WATER; WAVELENGTHS